ctrl-b to box in text mode

vim/vimbox

@@ -1,7 +1,8 @@
 #!/bin/bash
 function helpexit() {
-    echo Edit a file with check list mod of vim
-    echo "key 'b' adds a checkbox, space toggles the box"
+    echo Edit a file with check list mod of vim.
+    echo "Key 'b' inserts a checkbox, space toggles the box."
+    echo "Ctrl-b in editing mode inserts a checkbox."
     echo All switches are passed on to vim.
     exit
 }